Generally, integrated circuits and other semiconductor devices are used in a variety of electronic applications, such as computers, cellular phones, personal computing devices, and many other applications. Home, industrial, and automotive devices, which in the past included only mechanical components, now have electronic parts that require semiconductor devices.
Semiconductor devices are manufactured by depositing many different types of material layers over a semiconductor workpiece or wafer, and patterning the various material layers using lithography. The material layers typically include thin films of conductive, semiconductive, and insulating materials that are patterned and etched to form integrated circuits (IC's). There may be a plurality of transistors, memory devices, switches, conductive lines, diodes, capacitors, logic circuits, and other electronic components formed on a single die or chip.
Lithography involves the transfer of an image of a mask to a material layer of a die or chip, also referred to as a wafer. The image is formed in a layer of photoresist, the photoresist is developed, and the photoresist is used as a mask during a process to alter the material layer, such as etching and patterning the material layer.
The size and shape of features on the patterned material layer and photoresist are sometimes checked using a critical dimension scanning electron microscope (CD-SEM). The CD-SEM takes top-down images of the feature of interest with high-magnification. The contours of the patterned features may then be extracted from the images by processing the gray level pixels of the CD-SEM image.
Processing CD-SEM images involves analyzing complex shapes from images that often have poor image contrast and image noise. The complexity, contrast, and noise lead to high uncertainty in the extracted contours. Some methods average the extracted contours of dozens of CD-SEM images to improve the contour quality. These averaging methods, however, are not robust against large edge detection errors in single extracted contours that may largely influence the average contour.
As such, it is desirable to provide more robust methods and systems for averaging contours. Furthermore, other desirable features and characteristics of the inventive subject matter will become apparent from the subsequent detailed description of the inventive subject matter and the appended claims, taken in conjunction with the accompanying drawings and this background of the inventive subject matter.